1 / 11

Karel

Karel. Chapter 5. A new class!. We’ve been using UrRobot – knows only 5 things Let’s now use a new type of Robot: Robot! i.e. – public class MileMover extends Robot. Robot methods. frontIsClear () – boolean , returns true or false  checks if immediate front has wall or not

ami
Télécharger la présentation

Karel

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Karel Chapter 5

  2. A new class! • We’ve been using UrRobot – knows only 5 things • Let’s now use a new type of Robot: Robot! • i.e. – public class MileMover extends Robot

  3. Robot methods • frontIsClear () – boolean, returns true or false •  checks if immediate front has wall or not • nextToABeeper() – boolean • checks if corner it is on has a beeper • nextToARobot() – boolean • facingNorth() – • … south, east, west • anyBeepersInBeeperBag() • All methods are booleans!!!! • Still has all of UrRobot’s methods

  4. The If Method • Karel can make decisions for himself! • Syntax: • if(condition) • { <do some action>} • Example: • if(frontIsClear()) • { move();}

  5. If method • The parameter of the method (inside the brackets): • Any statement that will mean: if(true) or if(false) • Many ways to say true or false: • if(frontIsClear()) – if front is clear • If(! frontIsClear()) – if front is not clear •  !  exclamation point means “not”

  6. If-else • Useful if you want only 1 of 2 alternatives • Ex) if(frontIsClear()) • { • move(); • } //note – bracket is closed • Else • { • putBeeper(); • }

  7. Nested if’s • Necessary when multiple conditions need to be tested • Ex) if(nextToABeeper()) • { if(frontIsClear()) • {pickBeeper(); • move(); • } • } •  good idea to only limit nested if statements to 2 – 3 nests

  8. Nested if’s • What if: • If(facingWest()) • { if(frontIsClear()) • { if (nextToABeeper()) • { if (nextToARobot()) • }}} • We can fix this:: • If(facingWest() && nextToABeeper() && nextToARobot()) • Just use && (means AND) • Also - || means OR • These are called logical operators

  9. transformations • Test reversal • Bottom factoring • Top factoring • Redundant test factoring • All on pages 123-126  see how these work!

  10. Before problem set • All programs we have done have an issue where the robot might have an error shut off (ex – running into a wall) • Using our new methods, you should be able to reprogram the old programs to never have an error shut off •  try it with MileMover - reprogram move, pickBeeper, and putBeeper so they won’t have error shutoffs •  also – program Racer on page 123

  11. Problem set • Start to include comments: • Each program should start with: • //your name • //AP Computer Science • // Chapter 5, pr # • // 10/##/09 • Ch 5, #1, 2, 3, 6, 8, 9, 10, 11, 14 • --large problem set, we will spend a lot of time in class on it, but make sure to program at home as well

More Related